Versatic Acids and Derivatives. Solutions for Cover Title Longer Lasting 1 Brand (Rev) Wood Protection

Transcription

1 Versatic Acids and Derivatives Solutions for Cover Title Longer Lasting 1 Brand (Rev) Wood Protection

2 Wood is a very popular building material not only for exterior applications such as window frames and cladding but also for the creation of outdoor living space such as wooden patios, decks, fences and garden furniture. Without some type of protective surface coating, most wood will deteriorate very rapidly during outdoor exposure. Besides excellent resistance to weathering and UV, other features such as good adhesion to wood, protection against liquid water ingress and a good balance between hardness and flexibility are key requirements for exterior wood coatings. While solvent-borne alkyd binders have limited durability, they offer many of these properties and are therefore widely formulated into exterior wood coatings. Nevertheless, with increasing pressure to reduce the level of volatile organic emissions, acrylic-based waterborne systems are rapidly gaining popularity. Moisture protection, however, remains a critical parameter still to be optimized in the field of waterborne acrylic wood coatings. While various additives exist to increase the shortterm hydrophobicity of coatings, the incorporation of highly hydrophobic monomers into an acrylic polymer is an ideal and durable solution for enhancing the final wood coatings ability to repel water and resist to weathering influences. TM 1 Monomer 1 monomer is the vinyl ester of Versatic Acid 1, a highly branched and saturated carboxylic acid containing 1 carbon atoms. 1 vinyl ester is a monomer with a unique hydrophobic bulky structure and is used in the production of a broad range of high quality latex polymers. Structure and Properties Vinyl Ester n Easily copolymerisable with vinyl acetate, ethylene, acrylates and methacrylates. Versatic Acid 1 n Hydrophobic n Low surface tension n UV Resistant n Hydrolytically stable n Non-Hazardous Vinyl Ester of Versatic acid 1 R 1 + R = 7 carbon atoms Benefits of Vinyl Ester: vinyl ester improves performance by increasing water resistance, UV resistance and adhesion. A vinyl ester containing self-crosslinkable core /shell polymer imparts a superior exterior durability to wood coatings. Coatings based on these polymers can be formulated at very low VOC levels.

3 monomers readily copolymerize in emulsion with acrylate and methacrylate monomers to yield latices that are especially suitable for highperformance coatings. monomers significantly upgrade key performance properties of acrylic coating systems, such as water resistance, chemical resistance, adhesion and exterior durability. Typical examples of use include wood stains and wood coatings, gloss paints, exterior masonry paints, roof tile coatings, anti-corrosion coatings and protective concrete coatings. Core/Shell Technology Polymer Properties Core/Shell Process A two-stage process is used whereby first a combination of acrylic monomers are reacted followed by delayed addition of a mixture of acrylate and 1 vinyl ester monomers. Incorporation of specific functional monomers leads to stable 1-pack self-crosslinkable polymers that will cure at room temperature upon drying of the coating. A self-crosslinkable Veocryl polymer consisting of a hard core (glass transition temperature Tg of 5 C) and a soft shell (Tg of C), is a good example of a high performance waterborne binder for wood coatings. Upon drying a soft flexible Veocryl matrix containing hard acrylic domains will be formed. The hard pure acrylic core imparts a good blocking resistance, and the combination with the soft shell matrix, provides a very good balance between hardness and flexibility. With the hydrophobic bulky monomer present in the shell, the polymer and the resulting wood coatings offer a superior water resistance and water repellence, good adhesion and outstanding exterior durability. Strong Reduction Of Volatile Organic Emission Levels Careful selection of the monomers used in the shell enables the preparation of emulsions that form tough polymer films at temperatures as low as C. Wood coatings based on these polymers can be formulated with very low co-solvent levels and still form high quality coating films at very low application temperatures. In addition, the vinyl ester/acrylic core/shell polymers are formaldehyde free and also have a low residual monomer content of <5 ppm. This enables the development of a new generation of wood coatings with very low volatile organic emission levels. Core/Shell Process Tg C Stage 1 Core MMA BA Stage Shell 7% + BA 1 MMA BA Tg 5 C BA MMA MMA t Vinyl Ester/ Copolymers (Veocryls) Core/Shell: Hard core = blocking resistance Soft shell = flexibility, hydrophobicity Your Solution to Create Change in Chemistry.

4 Vinyl Ester Based Self- Crosslinkable Core/Shell Polymers Impart Long-Lasting and Superior Water Barrier Properties 1 vinyl ester monomer imparts protection against water and therefore also increases the durability of wood coatings. This is clearly demonstrated by comparing the performance of Veocryls versus benchmark acrylic emulsions. A series of selfcrosslinkable core/shell acrylic latices with a fixed core Tg of ~5 C and a soft flexible shell were prepared. The outer shell of the polymer particles were modified by incorporating either -ethylhexyl acrylate (-EHA) or 1 vinyl ester as hydrophobic monomers. In addition, two representative commercial acrylic emulsion binders for wood coatings were evaluated. Water Repellency Expensive additives such as special waxes or silicones are commonly formulated into wood coatings to provide them with a water beading effect. Often, the effect of these additives is only temporarily as they will gradually leach out of the coating. The incorporation of 1 monomer into the polymer backbone has a significant and long-lasting impact on the water contact angle and hence water repellence of the polymer. The water repellence behaviour of the 1 vinyl ester based systems is very pronounced and is very much superior to that of the -EHA based polymer or any of the other acrylic benchmark polymers tested. Early Water Resistance Early resistance to weathering is a requirement that exterior wood coatings must meet if they risk to be subjected to moisture or rain shortly after application. This moisture will typically cause blistering, loss of adhesion, or surface staining. The increased hydrophobicity of the vinyl ester containing polymer improves its early water resistance to levels above those of the other pure acrylic polymers. Composition and latex properties of the evaluated systems: 3 % vinyl ester: Core/shell polymer containing 3 % of 1 vinyl ester -EHA: Core/shell polymer containing 3 % of -ethylhexyl acrylate Benchmark 1 (BM1): A commercial high-end acrylic emulsion polymer tailored towards the decorative wood coatings market Benchmark (BM): A commercial high-end acrylic emulsion polymer tailored towards the industrial wood coatings market Typical Polymer Properties Property 3 % 3 % -EHA BM1 BM MFFT initial < C 9 C 15 C 7 Cw Particle size 11 nm 11 nm 1 nm 75 nm Water contact angle Typical Coating Properties Property Blocking (1 week dry) Adhesion on aged alkyd Tg shell C: Tg shell 1 C: 9 No detachment -EHA 9 1 5% detachment BM1 7 No detachment BM 9 No detachment SB Alkyd 5 Total detachment Core/shell Veocryls exhibit a long lasting and superior water repellency Water contact angle 3 % Water contact angle 3 % -EHA Performance Benefit vinyl ester strongly increases the water barrier properties and water repellency of wood coatings while maintaining a good water-vapour permeability.

5 VOC Compliant Wood Coatings Different acrylic binders were formulated into semi-transparent stains and white pigmented wood coatings. All these systems are compliant with the new European Union 1 VOC legislation (< 13g VOC / l). A commercial (SB Alkyd) 1 compliant highsolids solvent-based alkyd stain (< g VOC / l) was used as additional benchmark. Blocking Resistance The core/shell polymers have an equal or better blocking resistance than the commercial acrylic and alkyd benchmarks. By adjusting the Tg of the shell the blocking resistance can be further adjusted to meet specific needs. Resistance To Liquid Water Water absorption is a key driving force for expansion and contraction of wood, for mould growth and therefore also for wood degradation. The liquid water uptake into wood was tested for wood stains applied on Epicea wood. vinyl ester based wood stains have superior water barrier properties and significantly decrease the water uptake by the wood. From the water based systems the core/shell system has one of the lowest liquid water permeability values and is close in performance to the solvent based alkyd. Water Vapour Permeability Where a coating with a low water permeability clearly reduces the water uptake, it should at the same time be breathable to water vapour, and quickly release the moisture absorbed in the wood. vinyl ester based polymers not only provide an excellent barrier to liquid water, but more importantly do this without negatively affecting the moisture vapour permeability of the wood stain. Overall the combination of repelling liquid water and releasing water vapour is of great value to create effective protection against water attack. Liquid water permeability of wood stains (EN 97-5) Water vapour permeability of wood stains (ASTM D ) 35 7 [g/m after 7 h] [g/m / h] EHA BM1 BM SB Alkyd -EHA BM1 BM SB Alkyd Early (1h dry) water spot resistance 1 Early water spot resistance -EHA BM1 BM 1 = film unaffected / = film completely white Your Solution for Superior Water Resistance.

6 Vinyl Ester Based Self- Crosslinkable Core /Shell Polymers Enable the Development of Wood Coatings With A Superior Durability And Weathering Resistance. Wooden articles intended for exterior use are exposed to severe UV-radiation, rain and temperature changes. Coatings for exterior wood therefore need to have a long-term weather stability. The different wood stains were evaluated in accelerated weathering for h according to EN 97- by an independent leading testing and certification institute for wood coatings (CATAS). Accelerated Weathering The wood stain based on the /acrylic core/ shell polymer significantly outperformed the stain based on the -EHA containing polymer and was superior to any of the other systems tested. The good retention of the appearance of the vinyl ester based coatings after artificial weathering is not only very visible but can also be clearly quantified by minimal colour change and the excellent gloss retention of the formulated stain. Natural Weathering The /acrylic core/ shell systems also shows excellent performance during natural weathering, and whereas the tests are still ongoing, they have currently reached 3 years of exposure without any significant performance loss. Accelerated weathering - Colour changes ( h EN97-) Accelerated weathering - Gloss retention ( h EN97-) 5 7 [delta E*] 15 1 [%] EHA BM1 BM SB Alkyd -EHA BM1 BM SB Alkyd For Longer Lasting Wood Protection Use Vinyl Ester Based Emulsions. vinyl ester enables the development of exterior wood coatings with a superb exterior durability.

7 Vinyl Ester Helps You Developing Sustainable Solutions Characterized by n A superior and longlasting water repellent effect n Low liquid water uptake combined with good water vapour permeability n High exterior durability through excellent resistance to cracking, peeling and blistering, and good adhesion combined with adequate flexibility. n An improved environmental friendly system with low solvent demand, low residual monomers levels, and free of formaldehyde and APE-surfactants. Ideal for Transparent Stains and Pigmented Wood Coatings for: n Fences n Siding n Garden furniture n Decking n Industrial joinery (window frames) /acrylic polymers are also ideal binders for the formulation of high performance anti-corrosion coatings, protective concrete coatings, exterior masonry paints and roof tile coatings. Liquid Water Permeability 1 Liquid Water Permeability 1 Liquid Water Permeability 1 Adhesion Water Spot Adhesion Water Spot Adhesion Water Spot DE* Blocking DE* Blocking DE* Blocking Gloss Retention Gloss Retention Gloss Retention Adhesion DE* Liquid Water Permeability Water Spot 1 Blocking Performance comparison summary of wood stains -EHA BM1 BM SB Alkyd Gloss Retention Your Solution for Longer Lasting Wood Protection. -EHA BM1 BM SB Alkyd test protocol #

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